Oxidation of lower aliphatic alcohols



July 11, 1944. D, c, HULL 2,353,158

' OXIDATION OF LOWER ALIPHA'I'IC ALCOHOLS 1 File d June 29, 1942 FEED METER u I 1 E 27 NDENSER gm 1 v 8 5 STEAM f 9 21 W fza SEPARATOR /24 ,wxwxnou UNIT PACKED 12T 22 SCRUBBER Y RECEIVER 3- L 14 1 6 RECEIVER ==1 4=== I OXIDIZING MEDIUM DAVID HULL INVENTOR WJZnJN BY AMQ/( XK ATTO EYS Patented July! 1, 1944 UNITED STATES PATENT OFFICE zassnss' Y mm 0. Hull, Kingsport. ma,- assignmto amman Kodak Company, Rochester, N. 1., a corporation of New Jersey Application June 2d, 1942, Serial No. 44am 3 Claims. (o1. zoo-s31) This invention relates to the direct oxidationof organic compounds, particularly the oxidation of hydroxy compounds such as lower aliphatic alcohols oxidized directly to acids.

This invention is a continuation-in-part of my allowed application, Serial No. 228,822, flied September 1, 1938, nowPatent No. 2,287,803.

As pointed out in connection with the aforementioned companion application, in the prior art oxidation processes have required employingrelatively high temperatures such as 300 C. or

400 C. and the application of several steps. In other words, the oxidation either has not been direct, or if there has been direct conversion, the

' yields have been very law. For example, considering prior art-procedure for converting ethanol ered necessary to first dehydrogenate all of the ethanol and thereafter the aldehydic dehydro genation product was converted to the acid which, as can be seen, involves a number of steps.

Carrying out oxidation processes in accordance with the prior art possesses a number of disadvantages exemplified, for example, by the required use of relatively high temperatures. Also there may in some instances be the dis- Q a .to acetic acid, before my inventionit was considhols alone or mixtures of alcohols and aldehydes, or other typesof mixtures. A still further object advantage of polymerization of the products of .1

is desirable, particularly under present conditions, to develop a process in. order that other metals may be employed and the process improved in other respects, as will be apparent from the description whichfollows.

single step. Still another object, however, is to provide a process which may also be applied to,

not only the monohydroxy alcohols, but to the Y polyhydroxy alcohols and other similar organic compounds. Another and izvarticular object of this invention is to provide a direct oxidation process which may be operated at relatively low temperatures and under ordinary pressure conditions, yet give very satisfactory yields of the desired oxidation products. Still another ob-.

Ject is to provide a direct oxidation process for the conversion of alcohols to acids wherein the alcohol may-be converted, not only to an acid having a number of carbon atoms corresponding to the number of carbon atoms in the alcohol molecule, but also too different acid. A still further object is to provide a process which may be operated under other than normal atmospheric conditions, namely, under either superatmospheric or reduced pressures.

A further object is to provide a direct oxida-' tion process that may be applied to either aim is to provide a direct. low-temperature oxidation process which may be applied to vari'ous mixtures of alcohols and aldehydes wherein both the alcohol and the aldehyde are converted into useful oxidation products. Another object is to provide a direct oxidation process, particularly adapted to the treatment of alcohols such as butyl alcohol and the' like wherein, not only may butyric acid be obtained. but contents of other acids.

A further object is to provide novel catalysts containing liquids particularly adapted for employment in the aforesaid type of processes for the direct conversion of alcohols alone, or alcohols in various admixtures, into useful oxidation products. A still further, object isto provide methods for producing the catalysts as well as for activating and utilizing the catalysts.

After further investigation I have found that there are certain other catalytic materials which may be employed in direct oxidation processes in a er akin to the procedure set forth in my companion application which not only permits obtaining direct oxidation, but permits the production of a relatively larger variety of products than has heretofore been obtainable.

The invention has for one object to provide a As already indicated, prior to my invention, if an alcohol were t'obe oxidized it was generally first dehydrogenated and then the dehydrogenation products further treated. In any event prior art processes as ap e to alcohols usually process for the direct oxidation of organic compounds. Another object is to provide a' direct oxidation process which is particularly valuable for the direct conversion of lower aliphatic alcohols to lower aliphatic acids in substantially a of 300 C. which, not only requires substantial heat input but, due to. the higher temperatures and other conditions required in handling chemicals, involves dangers of loss from polymerization or otherundesired reactions. Also apparatus destruction may be more severe.

I have found that contrary to such procedure an organic con'ipound, exemplified in particular 2 by a hydroxy compound as a lower aliphatic alcohol, may be directly oxidized at relatively low temperatures, even temperatures substantially below 100 0., with any of the usual oxidizing mediums of which the commonest one, namely air,

.may be readily utilized in my process. Also my process, after it is placed in operation, does not usually require any heat input but generates sufficient heat itself to maintain the reaction. Not only may single organic compounds be treated,

but various mixtures of the organic compounds may be treated. For example, I have found that a mixture comprising a lower aliphatic alcohol, together with a corresponding or a, different aldehyde, may be efficiently treated by my novel process and catalyst to give very high yields of I aliphatic acid. By my process and choice of catins. The attached figure may be considered a semi-diagrammatic side elevation view showing a general apparatus arrangement which could be employed for carrying out my process.

Referring to the drawing, 2 represents an oxidation unit which may comprise any of several different constructions. For example, the preferred external construction would, in a large. diameter unit, be in accordance with Hasche Patent 2,159,988. However, the construction may be a sieve plate column, bubble plate column, or other comparable arrangement for permitting the contact of an oxidizing medium containing free oxygen with the material to be oxidized. In the unit shown in the attached figure the column merely comprises an elongated, open column of relatively narrow dimensions. Attached to the lower part of the unit at 3 and 4, are cooling jackets provided with inlets for cooling medium as at t be circulated in the event that high boiling components are being directly oxidized or the reaca branch conduit 20 through which non-condensables may be conducted to the scrubber it.

The aforementioned scrubber is provided with a receiver II at the lower part thereof and vent conduit 21 from the upper part thereof, which may lead through a meter or other device for measuring and testing the emuents.

There may also be associated with the apparatus thermometers or other temperature controlling devices or various exchangers for recovering heat or otherwisejfacilitating or rendering the operation of the process more economical,

or permittlng it to be operated with automatic control. Hence, my invention is not to be restricted in these respects.

I have folmd that certain metal compounds, .as for example, esters derived from metals of the aluminum and rare earth groups may be incorporated in acidic solutions and that these solutions will function as a catalyst medium for the direct oxidation of organic compounds. That is, an-alcohol alone or alcohol and other organic compounds to be oxidized, may be passed into a catalyst solution, as aforementioned, in the presence of oxidizing medium containing free oxygen and that the alcohol may be directly oxidized to acid, as will be observable in greater detail from the specific examples which follow.

Referring to the various metals which may be employed in accordance with my invention, there may be mentioned aluminum, thallium, indium,

and gallium.

ing that a is desired to convert an alcohol such,

as ethanol or butanol directly to the corresponding aliphatic acid, the derivativeof the catalyst metal would preferably be chosen corresponding to this acid; For example, in the instance of producing acetic acid there may be employed metal compounds such as aluminum, thallium or other acetates, depending upon the particular metal or metals employed.

Further examples of metal derivatives which may be employed for producing the catalyst solution temperature is to be held lower than that which would maintain a constant volume of catalyst. Inasmuch as the construction is substan-- tially the same, howeve the mechanical construction would be approximately the same and an inlet provided at I, I, and ii outlets are provided at II, II, and I3. As indicated, if desired in place of the external jackets, coils may be included within the unit and in large-size units such arrangement wherein internal coils, or both coils and Jackets are employed, may be desirable.

The lower part of the unit is provided with a plurality of inlet conduits, namely, inlet conduit M which is connected with a temperature-con dizing medium.

The upper part of the unit is provided with a drawofl conduit I! which leads through condenser il into separator II. This separator has attached thereto a receiver 22 for condensate and trolled feed supply It. Alsoleading into the lower part of the unit is an inlet conduit II for oxi-- tion are gallium acetate and indium butyrate.

While the aforementioned metal derivatives may be employed in various organic liquids,

which are solvents therefor, for simplicity of operation and minimizing the necessity of complicatcd separations I prefer to dissolve the catalyst compound in a liquid principally comprised of one of the materials which is to be produced in the process. For example, in the event my, process was to be applied in converting butyl alcohol directly into butyric-acid I would preferably dissolve the catahrst compounds in an aliphatic acid such as butyric acid. However, 'propionic' or acetic acid couldalso be used. However, for initially preparing the catalyst solution other liquids could be employed, as for example, organic esters and the like such as butyl or ethyl acetate.

In any event, irrespective of the exact metal compound and the liquid that the compound is dissolved in, the catalyst solution would be given a vigorous oxidation treatment such as blowing with a substantial amount of air usually for e periodofat least 5 or'lO minutes, and if desmd, for several hours. This treatment would preferably be accompanied by the introduction of an aldehyde along with the oxidizing medium and functions to convert the metal ions of the catalyst metal into a higher stateof .valence than their lowest valence. The treatment maybe ac-, companied by heating obtained in any convenient manner such as by flowing a heating in the jackets or coils in association with the oxi datlon unit or by introducing heated air. The

temperature of treatment, however, may vary from around cup to the boiling point or the particular liquid present.

After the catalyst liquid containing ametal selected from the aluminum and rare earth group metals, as already described, has been treated and brought to a starting temperature, usually above room temperature but below around 100 0., the organic compound'to be oxidized may be supplied tothe process.

That is, referring to the attached drawing, the'oxidation column 2 is filled with the cata-' lyst liquid comprising one or more aluminum or' rare earth metal compounds of the type described dissolved in solvent and maintained at the desired temperature; The hydroxy compound to be oxidized is introduced into the oxidation process through conduit l4 and the oxidizingmedium, usually air (however'pure oxygen or ozone may be employed and appear to render the catalyst solution more active, but are not necessary) and the compound oxidized to one or more desired oxidation products, as will be described hereinafter.

Assuming that the oxidation product is-a liquid,

' a portion thereofmay be volatilized or pumped oil throughv conduit I! through the condenser I! I where condensables are condensed out to be collected in receiver 22. The unconsumed gases (as nitrogen when-air is used in oxidizing'medium) unoxidized organic compound and the like,

1 components, uncondensed, pass through conduit 28 into scrubber II where they are recovered.

While only a single scrubbing unit has been indi- I or other recovery devices utilized.

The operation of my process to convert an cated, a plurality of such units may employed.

organic compound such. as butyl-alcohol to aliphatic acids and the functioning of variousof the aluminum. and rare earth metals'as cataassarsar M metal catalyst gave mgfl gag; proplonic acid. Whilea4% catalyst solutionhas Y been indicated, theiamount of. catalys may vary from a amount to a saturated solution, .but

examples whichfollow:

EzamplclII In accordance with this example solution is composed of 100 parts of soot and 2 parts of cerium acetate. v

in general;- amount of catalyst will; be main tainedbetweenmt or2%:and12%-.1- 1- foregoing examples aregillustretiver of oneof thepreferred applicationscoftmyproc ess, myprocess may be operated with the, serious 10 er c a ys s ei r ed o i'ier:- carious:-w

other conditions, be apparen from the having dissolved therein 2 partsof galliumacetat 1,000 grams of acetaldehyde and 500 gramslo' average yield of 80 225 grams of butyric acid and 40-100 grams of propionic acid as the major prodnets of the oxidation process. As in the precedingjexamples, the process wasoperated sothat the catalyst solution was maintained in the liquid phase. However, in the instance of alcohol, as

. butyl alcohol, it is possible, if it isdesired to operate with temperatures up to nearly 150, C that a higher temperature can be employed if pressure is applied to the reaction. In this reaction some excess oxidizing medium (air) may be 1 supplied to the reaction, so that a content of oxygen was indicated in the .01! cases.

When ethyl alcohol or propyl alcohol is used lower temperatures may be employed. Furthermore, the-pressure may be varied within rather wide limits without basically changing the process. Similarly, the catalyst may be employed as a salt or mixture of salts of any organic acid or acids, or a mixture 0! the metals themselves maybe employed.

In the foregoing examples there was some alcohol left unchanged which maybe recovered either I in the scrubber or otherwise. As indicated, while at normal atmospheric pressure a temperature under 100 0., and in many instances between 30 C. and 0., appears to be quite satisfactory. I 50 the process may be caused to, operateeven at temperatures as. low-as -5 C. and up to they boiling point ofthe catalyst solution. i In preferred operationusing, for example, the air as an oxidant, this may be supplied under The foregoing examples were carried out in apparatus as indicated in the attached drawing and at a temperature between 30 C. and 50 C. 70

It will be observed that the catalyst indicated gave yields of propionic acid in addition to butyricacicl, although butyl alcohol and acetaldehyde were the materials processed. It will also be observed .that apparently the aluminum and rare lysts is believed quite-clearly illustrated by the some pressure and if desired a rather substantial data appearing in the following table: excess can be incorporated, although for normal Per cent Wei t I eight ff," Weight was: P: cont Per cent Mm] we int e "'35" as a? can:

on led produced produced add I Grins 6min. Grease 1.: var iai- 18.1 I iitiiiiiht:::::::::::::t 4 iii; in. a. .01 as m operations only an excess, so that a few percent 0! oxygen are indicated in the eilluents, would be employed. In the event of the use of other oxidauts such asrelatively pure oxygen'and ozone. smaller amounts are required and may be supplied under substantial pressure for causing them to fully permeate the entire catalyst solution.

While in certain of the telecoms examples we in place of or in admixture with butyl alcohol,

have indicated the utilization of butyl alcohol in admixture with .acetaldehyde, a comparable mix-.- ture .of ethyl alcohol and butyraldehyde may be processed in the same manner to-obtain a mixture of acetic and butyric acids. Similar remarks app y to the employment'of other mixtures at alcohols and aldehydes. That is, ethyl alcohol may be processed in admixture with acetaldehyde to produce relatively pure acetic acid. Or, for example, propyl alcohol may be processed inaccordance with the present invention in the presence of acetaldehyde, butyra'ldehyde, or propionaldehyde. However, inasmuch as acstaldehyde is in many instances most readily available and has a low boiling point, it would preferably tions except that in some instances, such as for saturating the catalyst solution with oxygen, 1 may apply'a few pounds pressure up to 2 or 3 atmospheres for this purpose. Also, as indicated, the process functions very well at ordinary temperatures of 30 C. to 50 C. However, by raising the temperatures above the range indicated and applying some increased pressure, larger amounts of alcohol may. be converted per pass per unit of time. Undersuch procedure the aldehyde feed would becorrespondingly reduced as the amount of-alcohol fed was increased.

As apparent from certain of the preceding examples one valuable aspect of the present invention is that acids having fewer carbon atoms than the alcohol being oxidized may be directly produced and the proportion of these other acids to the acid having the same number of carbon atoms as the alcohol being oxidized may be varied by choice of the particular catalyst, as apparent from Examples 1, II and 111 set forth above.

.It is apparent from the foregoing that my invention is applicable to the direct oxidation of 'the various organic compounds, particularly hydroxy compounds such as various alcohols.

necessitated by the prior art and the spirit the appended claims.

- aliphatic acid, which comprises treating a solu-.

The foregoing examples are merely illustrative of some of thematerials to which my low temperatu're liquid phase process may be applied, but various other compounds, such as hydroxy alcohols exempliiied by glycols, may be treated in a comparable manner. Hence, I'do not-wish to be restricted in'my'invention excepting insofar as is What I claim and desire to secure by Letters Patent of the United States is:

1. Aprocessi'orthedirectoxidation of alower aliphatic alcohol to obtain the corresponding aliphatic acid, which comprises treating a solution of a metal ion of a metal of the aluminum group in an aliphatic acid with an aldehyde and a gaseous oxidizing medium to form a catalyst solution, introducing material amounts oi a lower aliphatic alcohol and a lower aliphatic aldehyde into the activated catalyst solution, oxidising the alcohol of the resulting solution of catalyst, alcom and aldehyde by treating me solution with a gaseous oxidising medium, maintaining the temperature ofthe solution of catalyst, alcohol and aldehyde during its treatment with the gaseous oxidising medium such that the solution is maintained in the liquid phase. and subsequently re covering the aliphaticacid produced.

2. A process for the direct oxidation oi a-lower aliphatic alcohol to ,obtain the corresponding tion of a metal ion of a metal of the aluminum group in an aliphatic acid with an aldehyde and a gaseous oxidizing medium to form a catalyst solution, introducing material amounts of a lower aliphatic alcohol and a lower aliphatic aldehydeinto the activated catalyst solution, oxidizing the alcohol oi the resulting solution of catalyst, alcohol and aldehyde by treating said solution with a gaseous oxidizing medium, maintaining the temperature of the solution of catalyst, alcohol and aldehyde during its treatment with the gaseous oxidizing medium such that the solution is maintained in the liquid phase at a temperature of from -5 to C. and subsequently recovering the aliphatic acid produced.

3. A process for the direct oxidation of a low aliphatic alcohol to obtain the corresponding aliphatic acid, which comprises treating a solution of thallium salt in an aliphatic acid with an aldehyde and a gaseous oxidizing medium to form a catalyst solution, introducing material amounts of a lower aliphatic alcohol and a lower aliphatic aldehyde into the activated catalyst solution, oxidizing the alcohol of the resulting solution of catalyst, alcohol and aldehyde by treating said 

